Dish machine monitoring of time, temperature, alkalinity, and pressure parameters

ABSTRACT

A dishwasher control system for automatically recording the duration of machine operation to determine cost of supplies, service and use. Machine operation is commenced by sensing the pressure of dishes and stopped automatically at the end of the cycle. During operation, the wash water is continuously sampled and checked for low temperature, low detergent and low pressure.

United States Patent Robinson July 29, 1975 1 1 DISH MACHINE MONITORINGOF TIME, 3.18.2,440 5/1965 Widegren 58/145 R TEMPERATURE ALKALINITY AND3,406,695 10/1968 Perl 134/58 D 3,490,467 1/1970 GOI'C 6181.... 134/18PRESSURE PARAMETERS 1127.376 5/1972 Pickup 417/477 Inventor: Norman R.Robinson, 6902 Brighton Dr., Dublin, Calif. 94566 Filed: Aug. 31, 1973Appl. No.: 393,345

US. Cl. 134/10; 134/18; 134/25 A; 134/56 D; 417/477 Int. Cl. B08b 3/10Field of Search 134/18, 10, 25 A. 25 R, 134/29, 30, 32, 57 D, 58 D, 72,56 D, 48; 417/474, 477; 58/145 R References Cited UNITED STATES PATENTSLow 134/57 D Meeker et a1 134/48 X Primary Examiner-S. Leon BashoreAssistant Examiner-Richard V. Fisher Attorney, Agent, or Firm-Limbach,Limbach & Sutton [57] ABSTRACT A dishwasher control system forautomatically recording the duration of machine operation to determinecost of supplies, service and use. Machine operation is commenced bysensing the pressure of dishes and stopped automatically at the end ofthe cycle. During operation, the wash water is continuously sampled andchecked for low temperature. low detergent and low pressure.

13 Claims, 4 Drawing Figures PATENTEU JUL2 9197.5

SHEET PATENTED JUL 2 9 I975 SHEET FIE:-

DISH MACHINE MONITORING OF TIME, TEMPERATURE, ALKALINITY, AND PRESSUREPARAMETERS BACKGROUND OF THE INVENTION Commercial dishwashing machinesare widely used in restaurants and hotels. These machines avoid therequirement for operators handling dishes and contacting detergentsagainst their skin and they operate much more rapidly than manualsystems. But commercial machines usually require a number ofoperatorinitiated steps. For example, with most commercial dishwashingmachines the operator must close drain valves; open fill valves and tillthe tanks to the proper level; install accessories, such as scrap traysand divider curtains; close inspection doors; turn on tank heaters; andturn on pumps and conveyor. After carrying out all of these steps, theoperator then proceeds to wash the dishes by inserting racks filled withdishes or by loading and unloading a continuous belt.

Most commercial dishwashing machines have dispensing systems associatedwith them to provide detergent to the machines at proper concentration.The wash water is monitored to provide a check on conductance of thealkaline solution. When the detergent level, as measured by alkalinity,falls below a predetermined level, the dispenser systems automaticallyadd the necessary dishwashing additives. However, the dishwashingoperator must keep the dispensing system stocked with detergents andadditives and must be trained in the operation of the dispensing systemas well as the dishwashing machine.

Previous dispensing systems are designed to add detergent and additivesduring the wash cycle whenever alkalinity is low. Occasionally the drainvalve to the dishwashing machine is inadvertently left open anddetergent-containing water is passed to waste. The addition of freshwater to restore the water level dilutes the detergent. Fresh detergentis added at each wash cycle because the conductance measure indicatesthat the detergent level is low. If the conductance measuring device isnot immersed in water because of low water level, it will signal lowcharge and cause more detergent to be added.

Another common problem with existing dishwashing machines is that theytend to be operated over greater periods of time than are necessary. Inmany installations, the machine is turned on in the morning with thefirst breakfast dishwashing and remains in continuous operation untilthe last dishwashing operation after dinner. During this entire time,the immersion heaters are on to maintain the water temperature at thedesired level. Continuous operation of the heaters tends to wasteconsiderable electricity and raise the ambient temperature levels in thedishwashing room. Similarly, bearings, motors and other moving partstend to have a shorter useful life when the machine is continuouslyoperated.

It is an object of the present invention to provide a dishwashingmachine control system that will reduce the time of operation to thatessential for cleaning of dishes; that will dispense dishwashingadditives in amounts necessary only for the efficient operation of themachine; and that will prevent most of the operator-caused waste andinefficiency currently found in the operation of dishwashing machines.

SUMMARY OF THE INVENTION The present invention involves a method andapparatus for controlling the operation of automatic dishwashers bycommencing operation only when dishes to be washed are present at theloading station and stopping the operation of the dishwashing machine atthe conclusion of the measured cycle as the dishes reach the unloadstation. The apparatus measures and records the duration of operation ofthe dish machine as a check upon the efficient operation of the machineand as the basis for charging for the use of the system. Circulatingdishwashing water is continuously tested during operation of thismachine for temperature, alkalinity and pressure. The temperature testprovides a convenient check on whether the wash water is hot enough forproper cleaning and as a check upon malfunction of the heater system.Alkalinity provides a convenient check on whether soil removal capacityof the circulating liquid is adequate. Testing for pressure determineswhether the cleaning action of the dishwashing water is satisfactory,since the presence of large amounts of protein in the wash water tendsto create high foam levels reducing the cleaning effectiveness of theliquid, even when it has adequate detergent levels. Pressuredetermination also senses whether there is a low water level conditionin the tank or an open or leaking drain valve. The system may alsoinclude sensors for an open fill line to prevent waste of water andexcessive dilution of detergent and for indicating low supply levels.Where any of the frequently recurring problems with automaticdishwashers occurs, the system automatically signals and sounds an alarmfor operator correction.

BRIEF DESCRIPTION OF THE DRAWINGS- FIG. I is a schematic drawing of aconventional commercial dishwashing machine.

FIG. 2 is a perspective view of the control box used for operating theconventional dishwashing machine according to the present invention.

FIG. 3 is a detail cross-section of the blending device of theinvention. 7

FIG. 4 is a plan view of the exterior of the control box.

DESCRIPTION OF THE PREFERRED EMBODIMENTS There are a wide variety ofcommercial dishwashing machines available today having manyconfigurations. Many features are common to the usual machines as to thearrangement of washing stations and operation. FIG. I schematicallyillustrates the typical dishwashing machine.

The dishwashing machine comprises a housing 11 through which a conveyormeans 12 passes. Conveyor means 12 is illustrated as a continuous belt,but other transport means, such as a reciprocating rod with pawlsengageable on specially made racks, are sometimes used to transportdishes through the housing 11. The machine shown is divided into severalstations, including a loading station 13, a pre-wash or scrapper stationI4, a wash station 16, a power rinse station 17, a final rinse station18 and an unload station 19. Dishes are placed on the conveyor means 12at station 13 either directly or in racks designed for use with theparticular device. In the present invention, it is desirable to commenceoperation of the dishwashing machine by sensing the presence of dishesto be washed at station 13. Normally, commercial dishwashing machineshave no such sensing devices built in and must be manually started bythe operator. I prefer a trip switch 15 conveniently located to beactuated upon placing racks of dishes or the dishes themselves on theconveyor means 12. While a trip switch 15 is convenient, othermechanical sensing devices may be used such as electromagnetic sensors,weight-sensing means, etc. Activation of the sensing device starts thedishwashing cycle, including operation of the conveyor 12 and therecirculating pump presently to be described. Trip switch 15 also causestimer 20 (FIG. 2) to operate.

Dishes to be washed first enter scrapper station 14 in which a largeflow of water from spray heads 21 and 22 flush large pieces of food fromthe surface of dishes to wet the surfaces and to remove debris. Not allcommercial dishwashers have a pre-wash or scrapper station 14, in whichcase the dishes proceed immediately into the wash station 16. Each ofthe stations has a tank for receiving water recovered from the sprayheads and appropriate means for removing contaminated water andrecirculating relatively clean water to the extent possible. Since thefunctions of scrapper station 14, power rinse station 17 and final rinsestation 18 form no part of the present invention, detailed descriptionand illustration of these stations is here omitted.

After large particles are removed at scrapper station 14, the dishespass on conveyor 12 into wash station 16. There, the dishes are sprayedwith detergentcontaining water from heads 23 and 24. To conservedetergent, it is recirculated by means of recirculating pump 26. Pump 26is located beneath the water level 27 in tank 28 of station 16. Pump 26has an inlet 29 and an outlet 31 which forces water to spray heads 23and 24 through pipes 32 and 33. Tank 28 has a fill line 36 for freshwater inlet and a drain line 37 for removing waste water, both withappropriate valves (not shown) for inlet and outlet of water.

Detergent and other appropriate dishwashing additives are stored remotefrom the dishwashing machine. As illustrated in FIG. 1, a typicaldishwashing machine has a container 38 for detergent, container 39 forchlorinated additive 39, and perhaps a container 41 for wetting agent orother additives. Of course, any number of additives may be provided,either more or less than the three illustrated in FIG. 1. Each container38, 39 and 41 has associated piping 42, 43 and 44 for supplying theadditives to the tank 28, as by gravity. The typical dishwashing machinehas valve means (not shown) for providing the appropriate amount of eachadditive to the liquid in the tank.

Following washing at station 16, conveyor 12 moves the dishes into powerrinse station 17 where relatively clean rinse water is sprayed on thedishes from spray heads 46 and 47.

In the embodiment illustrated, there is an additional final rinsestation 18. While all dishwashing machines usually have a wash station16 and a final rise station 18, larger machines ordinarily have scrapperstation 14 and power rinse station 17 in addition. In final rise station18, a second rinse is sprayed from heads 48 and 49 onto the dishes.Frequently, the rinse water in station 18 contains a wetting agent, suchas a nonionic surfactant, to promote sheeting and smooth drying of thedishes. The rinse additive may contain some alcohol to promote quickdrying. Such additives may be introduced to final rinse heads 48 and 49from one of more containers 51 through appropriate piping 52 and thenecessary metering means, valves, pumps, etc. (not shown).

After the final rinse station 18, conveyor 12 passes the dishes todischarge station 19 where the dishes are unloaded. When the dishesreach station 19 the machine will turn off and conclude the cycle. Themachine is turned off by operation of a timer 20 (FIG. 2). The timer isreset by the trip switch or other means sensing the presence of dishesat station 13. The timer then runs for the exact period of time forwhich the dish machine cycle is designed. Timer 20 is variable to runfor any duration of cycle that commercial dish machines have. An exampleof a suitable timer 20 is that made by AMF Corporation, Potter andBrumfield Div. under the designation CI-IB 38. The timer 20 is installedin control box (FIG. 1), which may be locked to prevent access by theoperators. Timer 20 is set at the time of original installation of thecontrol system to coincide with the normal cycle of the dish machine.Some existing machines remain in continuous operation until the operatorswitches the device off. According to the present invention, it isimportant to automatically turn the device off at the conclusion of thecycle because the time of operation of the machine is measured andrecorded to determine the cost of operation of the system.

Aside from the importance of having a recorded knowledge of the durationof operation of the device for efficient operation of the machine andmanagement time studies, it is convenient to service the machinesaccording to time. While presently available commercial dishwashingmachines are frequently serviced by businesses other than the owner ofthe machines, payment for the service of providing detergents andsupplies to the machine is presently on the basis of materials used,maintenance calls, etc. The present invention has particular importancein permitting service of dishwashing machines by supplying repairs,detergents, training, etc. charged for exclusively on the basis of timeof operation of the machine. Such a method of charging is moreeconomical and equitable to the owner of the machine and avoids the riskof substantial losses of detergents and damage to the machine whereoperator error occurs, such as by leaving the drain valve open or othererrors described above. The risk of detergent loss, control systemfailure, etc. is shifted to the service organization from the owner.

FIGS. 2, 3 and 4 illustrate the control system of the present invention.FIG. 2 shows the interior of the control system of the presentinvention. A sample of dishwashing water is taken from the circulatingliquid at station 16. Preferably, the sample is taken by tapping aone-eighth inch hole in the outlet manifold 31 of pump 26 (FIG. 1). Thehole may conveniently be connected to a PVC tube which passes to mixingmanifold 56 (FIG. 2). Sample water taken from a line at the exit end ofthe circulating pump or elsewhere is fed through line 57 into mixingmanifold 56 and returned to tank 28 of washing station 16 through exitline 58. Preferably, sample water passes through the control systemshown in FIG. 2 through line 57 and returns via line 58 during theentire time of operation of the circulating pump in the wash tank. Alldishwashing additives are introduced at the mixing manifold 56, therebyrequiring only an inlet line 57 and outlet line 58 connecting thecontrol system to the dishwashing machine. Even though any number ofadditives may be introduced into the dishwashing liquid, all suchadditive lines lead only to the control box shown in FIG. 2 and need notbe connected to the dishwashing machine itself.

Thermostat 59 has an electrode inserted into mixing manifold 56 fordetermining temperature. The probe of the thermostat 59 also serves asone electrode for determination of conductivity of the solution inmixing manifold 56 for alkalinity determination. Wire 61 is connected tosensitivity circuit 62. Wire 63, also connected to the sensitivitycircuit 62, leads to a second electrode 64 inserted into mixing manifold56. Sensitivity circuit 62 measure the conductance and, when alkalinityfalls below a predetermined level, introduces detergent additives byactivating the pump 66. Sensitivity circuit 62 consists of means toamplify the conductivity signal across the detergent solution inmanifold 56 between the two electrodes and, if the signal is weak.switching on the pump. When conductivity is restored and signal strengthincreases, circuit 62 turns off pump 66. In practice, I use an amplifierand control circuit consisting of a transistorized gate and apotentiometer to adjust the circuit to the desired concentration atwhich a relay activates the detergent pump 66. Any other suitable meansfor determining conductivity and commencing pump operation when a lowalkalinity condition exists may be substituted.

Conductivity circuit 62 commences operation of pump 66 when the level ofconductivity falls below the predetermined level. Sensitivity circuit 62is connected to pump 66 by appropriate switch means and wires (notshown).

Pump 66 is a peristaltic pump. Sensitivity circuit 62 commencesoperation of a small motor (not shown) which rotates drive shaft 67 towhich wheel 68 is attached.

Wheel 68 has three rods attached to its periphery to mark the corners ofan equilateral triangle. The three rods 71, 72 and 73 serve to pumpdishwashing additives into mixing manifold 56. FIG. 2 shows three rods,but any suitable number of two or more rods may be affixed to the wheel68. Rods 71, 72 and 73 may conveniently be made of nylon or othersuitable material. Lines 74, 75, 76 carry appropriate dishwashingadditives from containers 38, 39 and 41. These three lines are made offlexible tubing, such as one-fourth inch diameter polyvinyl chloride.Line 74 is attached to replaceable tube 77 by means of appropriateconnector 78. Line 77 is designed to be detachable from line 74 forreplacement with a similar line of different diameter. In this manner,the relative proportions of dishwashing additives may easily be variedby the simple expedient of substituting tubes of greater or lesserdiameter, depending upon the volume of the particular additive desired.Similarly, tubes 78 and 79 are detachably connected to lines 75 and 76,respectively, to permit substitution of greater or lesser diametertubing in order to enlarge or restrict the volume of additives to beintroduced into mixing manifold 56 from each line. Line 77 passesthrough grommet 81 in a hole through plate 82 and passes around rods 73,72 and 71 before passing out through plate 82 by means of grommet 83.Tube 77 then terminates and is detachably connected to line 84 by meansof a suitable connector 86, to permit easy substitution of line 77 witha tubing of different diameter. Line 84, also of flexible tubing, isthen passed to mixing manifold 56 and enters through fitting 87.

Similarly, flexible tube 77 comes from another source of dishwashingadditive which may be incompatible with the first and is detachablyconnected to line 78. Line 78 passes through grommet 88 in a hole inplate 89 and then passes around rods 72, 73 and 71 before leaving thepump through grommet 91 in another hole in plate 89. Tube 78 isdetachably connected to line 92 in the manner similar to connector 78.Line 92 then passes to mixing manifold 56 and enters through fitting 93;

Likewise line 76 is detachably connected to line 79 which, in turn,passes through grommet 94, around rods 72, 73, 71, and then exits thepump through grommet 95 in a hole in plate 89. Line 79 is detachablyconnected to line 96 which passes to mixing manifold 56 and entersthrough fitting 97.

In operation, peristaltic pump 66 rotates around shaft 67 to force thecontents of tubes 77, 78 and 79 into mixing manifold 56. It will beobserved that clockwise rotation of pump 66 in FIG, 2 stretches eachtube as each of rods 71, 72 and 73 pass to a maximum distance from therespective grommets in plates 82 and 89, thereby forcing the liquiddishwashing additives contained in the tubes into mixing manifold 56.Pump 66 efficiently meters additives to the manifold with a minimum ofmoving parts in an extremely simple manner.

Sensitivity circuit 62 and all control circuits are also controlled bytimer 20 so that they are operative only while the dish machine isoperating. Otherwise, the sensing devices will have to have a standbyposition for periods when recirculating pumps and other dish machineparts are not working. It is convenient to have the timer control theoperation of the dish machine and its control system at precisely thesame periods.

While not shown in FIG. 2, the control box may conveniently containmeans for determining the existence of flow pressure in the fill line tothe washing machine. This may be accomplished conveniently by having aflexible plastic tubing from the fill line to a pressure switch locatedin the control box. A pressure switch designated M3218-4 manufactured bythe Hobbs Division of Stewart-Warner Corp. of Chicago, Illinois, hasbeen found to be highly satisfactory for this purpose. The pressureswitch may be electrically connected to the alarm system on the face ofthe control box as shown in FIG. 4. When the pressure switch senses thepresence of water flowing in the fill line and the system is operating alight will be turned on on the front of the control box. Alternatively,the pressure switch may be located at the fill line itself, rather thanin the control box, and electrically connected with. the light on theface of the control box to indicate water flowing in the fill line. Thepressure setting for activating the switch is variable betweenone-fourth to thirty pounds per square inch. I prefer to set thepressure for switch activation at between one-half and three-fourthspsi.

In those installations where rinse water additive is to be introduced atfinal rinse station 18, the control box may also contain a feed linefrom the final rinse additive storage 51 into the final rinse heads 48and 49. A separate pressure sensitive switch (not shown) activates pump100 (FIG. 2) which feeds additives into line 52 (FIG. 1). Suitabletimers and circuitry are well known to those skilled in the art forpumping rinse water additives into station 18. One acceptable pump is amotor driven positive displacement injection pump manufactured by PlexChemical Co., Union City, California.

FIG. 3 is a cross section of mixing manifold 56 illustrated in FIG. 2.Additive-containing wash water from tank 28 (FIG. 1) is taken offthrough sample line 57 at the outlet from pump 26. Referring to FIG. 3,line 57 preferably has a filter 101 to remove large particles from thesample water entering mixing manifold 56. Pressure switch 102 senses,through plastic tube 103, the presence of water flowing in line 57. Whenwater stops flowing in line 57 or a low pressure condition occurs whilepump 26 is running, pressure switch 102 activates an alarm system. Thealarm system consists of a light on the face of the control panel (FIG.4) as well as a bell to call immediate attention to the operator thatwater is not being pumped by pump 26. Lack of pressure in line 57indicates that there is no water in tank 28 or that excessive foam intank 28 is such that pump 26 is unable to maintain the water pressurerequired for efficient operation of the dishwashing machine. Pressureswitch 102 is electrically connected through wires 106 and 107 to thebell and light alarm system. The alarm does not sound when the machineis turned off, but only when the wash cycle is operating in station 16.Sample water in line 57 enters mixing manifold 56 through fitting 108into port 109 and into chamber 111. In chamber 111, the sample water istested for temperature and alkalinity. Thermostat 59 functions tomeasure the temperature and switch on a signal light when thetemperature of sample water falls below a predetermined level.Conveniently, that level is 150 F. The probe 112 of thermostat 59 alsofunctions as the anode for determining alkalinity. Probe 112 isconnected by wire 61 to a sensitivity circuit previously described. Theelectrode 64 extends into chamber 111 through fitting 113. Electrode 64is connected to a sensitivity circuit through wire 63 in order tomeasure alkalinity.

When alkalinity falls below a predetermine level, such as aconcentration of approximately 0.7 percent by volume, the sensitivitycircuit 62 commences operation of peristaltic pump 66 and additiveingredients enter mixing manifold 56 through lines 96, 92 and 84. Thepotentiometer in circuit 62 may be adjusted to any desired concentrationfor operation of pump 66 as conditions in the particular dishmachinewarrant. In practice, I find concentration between 0.5 and l.5 percentby volume to be suitable for most dishwashing conditions. Concentrationis determined chemically and circuit 62 set at the time of installationto the desired value at which pump operation commences.

Chamber 111 of mixing manifold 56 empties into venturi channel 116 whichthen passes through exit fitting 117 at the bottom of the manifold andthrough line 58 back to the wash tank 28. Venturi channel 116 hastapered sides to provide a slight acceleration of sample water passingthrough it to provide a slight suction on additive feed lines 96, 92 and84. The suction in venturi channel 116 serves only to drain lines fromthe peristaltic pump 66 in the event of failure of any of the tubesassociated therewith. Introduction of the additives to the sample lineis accomplished by means of the pump. However, when a tube such as tube77, for example (FIG. 2), breaks through long flexing in the pump, anyadditive in the tube 77 on the upstream side from pump 66 will drain bygravity back to the storage tank for the additive through line 74. Onthe other hand, assume that a break occurs on the downstream side oftube 77 from the pump rods. The small amount of additive in line 77 andassociated line 84 downstream from the break would drain back into thecontrol box were it not for venturi channel 116. Even a small amount ofmany detergent additives is sufficient to cause considerable corrosionhazard to personnel and damage to parts of the control box. As a resultof venturi channel 116, sufficient suction is provided in the sampleline downstream from the pump 66 to enable any dishwashing additives tobe drained from broken tubes without draining into the cabinet of thecontrol box.

In order to take maximum use of the venturi effect in channel 116, lines96, 92 and 84 empty into the channel just below the minimum diameterthrough ports 121, 122 and 123.

FIG. 4 is the cover of a sheet metal box 125 which conveniently housesthe control system at a location convenient for the operator of thedishwashing machine. The cover of the closed box is shown in FIG. 4 tohave lights responsive to the various conditions requiring attention ofthe operator. Light 126 is responsive to the pressure-sensitive meansand is appropriately designated. Light 127 is connected to thetemperature-responsive means and serves to light up when low temperatureis indicated. Light 128 is turned on when the fill line is in use bymeans of the pressureresponsive switch in the fill line. The operatorwill know to turn off the fill line by the existence of light 128. Ialso prefer to install an audible signal, such as a buzzer, in additionto the light 128. Light 129 turns on when the supply of dishwashingadditives is below the desired level. The operator will take thenecessary steps to replenish the supply of dishwashing additives. Inpractice, this is done by contacting the service representative whoprovides detergents to the control system. Light 130 turns on when thedishwasher is turned on to activate the heating system. Heaters or gasburners are used for raising the temperature of the wash water as inconventional machines. Unfortunately, dish machines are designed to havethe operator turn on the water heaters separately from the pumps andconveyors. Operators frequently leave the water heaters off and washwith luke-warm water because the dishes are too hot to handle undernormal operation. This is a common operator failure which is avoided inthis system by preventing machine operation except when the heaters areon. Light 130 indicates the machine is in an idle condition with hotwater and awaiting dishactuation. Light 130 also serves to prevent theheaters remaining on all night when the operator goes home.

FIG. 4 also shows an elapsed running time meter 131 which records thenumber of hours of accrued operation of the dishwasher for complyingwith maintenance schedules and for charging for use of the system andproducts in those instances where the service of the control system ofthe dishwashing machine is provided by someone other then the owner ofthe machine. The meter is wired to timer 20 to record the totaloperation of the timer which coincides with the operation of the dishmachine. If the timer is set for a period longer than the dish machinecycle, the customer unnecessarily pays for added time. If the timer isset for a shorter period, then the cycle will not be completed and thedishes will not reach unload station 19.

Finally, FIG. 4 shows a lock 132 for providing security to the controlsystem and preventing access to the system except by authorized persons,usually those associated with the business of maintenance and supply ofdetergents, rather than the operators whose errors frequently have givenrise to the problems sought to be solved by the present invention.

The foregoing specific embodiments are simply exemplary of the differenttypes of apparatus that may be used to control the functions of adishwashing machine. Other forms of apparatus may be used to perform thecontrol functions specified in the attached claims. The control systemprovides a safe, efficient and automatic operation essentially free ofmanual operations by an operator of the dishwashing machine.

I claim:

1. In a method of controlling continuous automatic dishwasher operationwherein the dishes are transported through a device comprising at leasta washing station and a rinse station and dishwashing additives areautomatically introduced into circulating dish washing liquid whichcontacts dishes at said washing station, the improvement comprisingcommencing washing operation by mechanically sensing presence of dishesto be washed, stopping operation of the device at the conclusion ofrinsing, measuring and recording the duration of operation of thedevice, continuously sampling the circulating dish washing liquid duringoperation of the device to automatically determine:

1. the temperature and signalling when a temperature is determined to bebelow a predetermined value,

2. alkalinity and adding dish washing additives to the circulating waterwhen alkalinity is determined to be below a predetermined value, and

3. pressure and signalling when pressure falls below a predeterminedvalue.

2. A method as in claim 1 wherein said predetermined temperature valueis 150 F. the predetermined pressure value is three-fourths psi and thepredetermined alkalinity value is 0.7 percent concentration by volume.

3. A method as in claim 1 wherein the device has a fill line, the stepof automatically signalling the presence of flow pressure in the fillline during machine operation.

4. A method as in claim 1 wherein dish washing additives to beintroduced into the liquid are in containers, the steps of automaticallysensing and signalling the depletion of additive supply in saidcontainers.

5. A method as in claim 1 wherein dishwashing additives areautomatically blended into the sample of circulating dish washing liquidas needed before the sample is returned to the main flow of circulatingliquid.

6. A method as in claim 5 wherein the automatic blending varies therelative proportion of additives depending on water conditions and useneeds.

7. A method as in claim 1 wherein dish machine operation is preventedexcept when wash water heaters are in operation.

8. In a control system for a dishwashing machine, at least one waterspray station, a conveyor for dishes, and a recirculating pump torecirculate wash water, the improvement comprising 1. means forenergizing the control system and starting the dishwashing cycle whendishes are ready for washing,

2. means for sensing water pressure and signal means, responsive to saidmeans for sensing, operable when pressure falls below a predeterminedlevel during operation of the control system,

5 3. means for testing level of washing additive in the wash water,means responsive to said testing means to add washing additive to washwater when below a predetermined level,

4. temperature sensing means for detecting a temperature below apredetermined level and signal means responsive to said temperaturesensing means to alert the operator to the low temperature condition,

5. switch means turning off the dishwashing machine at the close of eachcycle.

9. A system as in claim 8 including measuring means responsive to themeans for energizing the control system and to said switch means,whereby said measuring means measures the duration of operation of thedishwashing machine.

10. A system as in claim 8 wherein the dishwashing machine has a fillline, the improvement comprising pressure sensitive means in said fillline to detect the flow of water in said line and signal means to alertthe machine operator to the flow of water in the fill line.

11. A system as in claim 8 including multiple sources for dish washingadditives and flexible tubes for passing additives from each of themultiple sources to the dishwashing machine, the improvement comprisingpump means engaging said flexible tubes to pump the additives, said pumpmeans having a rotating driven shaft, a wheel rotatably mounted on saidshaft, two or more rods extending parallel to said shaft from theperiphery of said wheel, each of said flexible tubes passing over saidrods, and tension means for placing the length of flexible tube fromeach source passing over said rods under tension, whereby the contentswithin the tubes are pumped as the rods peristaltically stretch saidtubes upon rotation of the wheel about the shaft.

12. A system as in claim 11 wherein the tubes downstream of said pumpmeans enter a mixing manifold comprising an inlet chamber, a venturithroat and an exit chamber communicating to the dishwashing machine,whereby additives flowing from said pump means are accelerated throughthe venturi throat.

13. In a control system for a dish washing machine having a fill line, aloading station, at least one water spray station, a water heater, adish conveyor, a recirculating pump and recirculating water. theimprovement comprising 1. control means for commencing operation of thedish machine responsive to the presence of dishes at the loadingstation,

2. time measuring means to determine the duration of operation of thedish washing machine,

3. temperature responsive means communicating with recirculating waterfor determining low temperature,

4. a first pressure responsive means in said fill line for determiningthe presence of water in the fill line.

5. a second pressure responsive means in said recirculating pump fordetermining low pressure,

6. peristaltic pump means for blending additives into a linecommunicating with said recirculating water to restore conductivityabove a predetermined level, and

7. a conductivity responsive means communicating with said recirculatingwater activating said peristaltic pump when conductivity is low.

1. IN A METHOD OF CONTROLLING CONTINUOUS AUTOMATIC DISHWASHER OPERATIONWHEREIN THE DISHES ARE TRANSPORTED THROUGH A DEVICE COMPRISING AT LEASTA WASHING STATION AND A RINSE STATION AND DISHWASHING ADDITIVES AREAUTOMATICALLY INTRO DUCED INTO CIRCULATING DISH WASHING LIQUID WHICHCONTACTS DISHES AT SAID WASHING STATION, THE IMPROVEMENT COMPRISINGCOMMENCING WASHING OPERATION BY MECHANICALLY SENSING PRESENCE OF DISHESTO BE WASHED, STOPPING OPERATION OF THE DEVICE AT THE CONCLUSION OFRINSING, MEASURING AND RECORDING THE DURATION OF OPERATION OF THEDEVICE, CONTINUOUSLY SAMPLING THE CIRCULATING DISH WASHING LIQUID DURINGOPERATION OF THE DEVICE TO AUTOMATICALLY DETERINE:
 1. THE TEMPERATUREAND SIGNALLING WHEN A TEMPERATURE IS DETERMINED TO BE BELOW APREDETERMINED VALUE,
 2. ALKALINITY AND ADDING DISH WASHING ADDITIVES TOTHE CIRCULATING WATER WHEN ALKALINITY IS DETERMINED TO BE BELOW APREDETERMINED VALUE, AND
 2. A method as in claim 1 wherein saidpredetermined temperature value is 150* F. the predetermined pressurevalue is three-fourths psi and the predetermined alkalinity value is 0.7percent concentration by volume.
 2. means for sensing water pressure andsignal means, responsive to said means for sensing, operable whenpressure falls below a predetErmined level during operation of thecontrol system,
 2. alkalinity and adding dish washing additives to thecirculating water when alkalinity is determined to be below apredetermined value, and
 2. time measuring means to determine theduration of operation of the dish washing machine,
 3. temperatureresponsive means communicating with recirculating water for determininglow temperature,
 3. pressure and signalling when pressure falls below apredetermined value.
 3. means for testing level of washing additive inthe wash water, means responsive to said testing means to add washingadditive to wash water when below a predetermined level,
 3. A method asin claim 1 wherein the device has a fill line, the step of automaticallysignalling the presence of flow pressure in the fill line during machineoperation.
 3. PRESSURE AND SIGNALLING WHEN PRESSURE FALLS BELOW APREDETERMINED VALUE.
 4. A method as in claim 1 wherein dish washingadditives to be introduced into the liquid are in containers, the stepsof automatically sensing and signalling the depletion of additive supplyin said containers.
 4. temperature sensing means for detecting atemperature below a predetermined level and signal means responsive tosaid temperature sensing means to alert the operator to the lowtemperature condition,
 4. a first pressure responsive means in said fillline for determining the presence of water in the fill line,
 5. a secondpressure responsive means in said recirculating pump for determining lowpressure,
 5. switch means turning off the dishwashing machine at theclose of each cycle.
 5. A method as in claim 1 wherein dishwashingadditives are automatically blended into the sample of circulating dishwashing liquid as needed before the sample is returned to the main flowof circulating liquid.
 6. A method as in claim 5 wherein the automaticblending varies the relative proportion of additives depending on waterconditions and use needs.
 6. peristaltic pump means for blendingadditives into a line communicating with said recirculating water torestore conductivity above a predetermined level, and
 7. a conductivityresponsive means communicating with said recirculating water activatingsaid peristaltic pump when conductivity is low.
 7. A method as in claim1 wherein dish machine operation is prevented except when wash waterheaters are in operation.
 8. In a control system for a dishwashingmachine, at least one water spray station, a conveyor for dishes, and arecirculating pump to recirculate wash water, the improvement comprising9. A system as in claim 8 including measuring means responsive to themeans for energizing the control system and to said switch means,whereby said measuring means measures the duration of operation of thedishwashing machine.
 10. A system as in claim 8 wherein the dishwashingmachine has a fill line, the improvement comprising pressure sensitivemeans in said fill line to detect the flow of water in said line andsignal means to alert the machine operator to the flow of water in thefill line.
 11. A system as in claim 8 including multiple sources fordish washing additives and flexible tubes for passing additives fromeach of the multiple sources to the dishwashing machine, the improvementcomprising pump means engaging said flexible tubes to pump theadditives, said pump means having a rotating driven shaft, a wheelrotatably mounted on said shaft, two or more rods extending parallel tosaid shaft from the periphery of said wheel, each of said flexible tubespassing over said rods, and tension means for placing the length offlexible tube from each source passing over said rods under tension,whereby the contents within the tubes are pumped as the rodsperistaltically stretch said tubes upon rotation of the wheel about theshaft.
 12. A system as in claim 11 wherein the tubes downstream of saidpump means enter a mixing manifold comprising an inlet chamber, aventuri throat and an exit chamber communicating to the dishwashingmachine, whereby additives flowing from said pump means are acceleratedthrough the venturi throat.
 13. In a control system for a dish washingmachine having a fill line, a loading station, at least one water spraystation, a water heater, a dish conveyor, a recirculating pump andrecirculating water, the improvement comprising